Method of making shaped synthetic products



Patented Dot. 3, 1950 METHOD OF MAKING SHAPED SYNTHETIC PRODUCTS Nicolas Drisch and Rene Fays, Paris, France, assignors to Comptoir des Textiles Artificiels, a

corporation of France No Drawing. Application February 23, 1946, Serial No. 649,778. In France May 25, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires May 25, 1963 This invention relates to a new andimproved method of producing synthetic products. More particularly, it relates to a new and improved method of making shaped synthetic structures,

such as yarns, threads, filaments, bristles, foils, caps, bands and the like.

In the development of synthetic yarns and related products derived from cellulose, there has been a progressive improvement in the properties of the products, rendering them more and more similar to the natural products. In some cases, the synthetic products have even surpassed the natural products.

One of the serious defects of synthetic yarns, and especially regenerated cellulose products, is their considerable loss of strength on wetting with water. In general, regenerated cellulose yarns lose one-half their strength on wetting with water. It is true that the tensile strength of wool also diminishes on wetting with water, but the tensile strength of cotton, instead of decreasing, increases slightly under such conditions. Wetting, in addition to reducing the tensile strength of regenerated cellulose yarns, also produces considerable swelling which is considerably greater than that of cotton yarn and other yarns formed of natural fibers. The swelling of regenerated cellulose yarn by water is of the order of 100% or more, expressed as the weight of water absorbed by the dry material, whereas it is of the order of 30% for cotton. This swelling considerably reduces the tensile strength and resistance to friction (which is moreover also affected for other reasons) of regenerated cellulose yarns. It also decreases the resistance to chemical agents, particularly to alkalis and acids. Synthetic yarns, and especially those of regenerated cellulose, also difier from yarns of natural fibers in that the former are wetted very most immediately, whereas in a Wool fabric (having exactly the same structure and the same surface composition) the drops do not spread but slide along the fabric. The explanation of this phenomenon must be sought in the changes produced by the treatments which the initial cellulosic material undergoes during the course of manufacturing the synthetic yarns. The initial cellulosic material is a high polymer composed of bundles of long-chained molecules arranged more or less parallel to the axes of the fibers This molecular and supermolecular structure is 2 Claims. (,Cl. 18-54) destroyed to a great extent in order to permit dis solution of the cellulose material. To convert the solution into yarn under practical conditions, the solution must have certain properties which can only be acquired by degradationof the molecular chain, that is, by more or less shortening the chains. In spinning the solutions finally obtained, attempts are made to reconstruct orientated structures, that is, to create a new organization of cellulosic chains which were harshly treated by the different treatments to which they were subjected. The structures thus obtained difieredconsiderably from those present in the initial material. The obtained structures contain a large number of strongly polar hydroxyl groups having a great aflinity for water. The presence of many more polar groups in the synthetic yarns (particularly in regenerated cellulose yarns but more generally in all products obtained from solutions of cellulosic material or its derivatives) than in natural products explains the special behavior of the synthetic products in the presence of water.

Attempts have been made for a long time to eliminate the aforementioned defects in synthetic products (obtained from solutions of cellulosic materials containing free hydroxyl groups by spinning, molding, etc), such as yarns, continuous filaments, fibers, bristles, foils, casings, tubings, caps, bands, etc., by blocking the free hydroxyl groups .in the regenerated cellulose by one of the following processes:

(a) physical association of regenerated cellulose with ordinary resins or other hydrophobic material, either by introduction into the spinning solution, etc. or by incorporation into the yarn, the resins forming coatings or inert masses within the product and without reacting with the cellulose;

(b substitution of the free hydroxyl groups in regenerated cellulose by esterification, etherification, etc., or in general by hydrophobic groups;

(0) blocking the hydroxyl groups in regenerated cellulose with the formation of bridges between the chains, thereby increasing the general strength of the cellulosic structure.

The treatment of cellulosic substances containing free hydroxyl groups with formaldehyde or Cellulose radicalOCH2Ocellulose radical Stenosation actually produced products having an increased wet tensile strength and reduced swelling. However, this treatment can only be applied to finished products, and even then the conditions had to be maintained within very narrow limits in order to avoid formation of nonuniform or degraded products of little technical interest. Though stenosation increased the tensile strength of the product, nevertheless the elongation, resistance to friction and to knotting were greatly decreased. Additionally, the affinity of the product for dyes was materially affected irregularly and non-uniformly.

Another object of this invention is to provide a new and improved method of producing products obtained from solutions of cellulosic materials containing free hydroxyl groups.

A further object of this invention is to'provide a method of producing synthetic shaped structures, such as yarns, filaments, fibers, bristles, foils, casings, tubings, films, caps, bands, etc., formed of a cellulose derivative.

Other and additional objects will become apparent hereinafter.

For sake of convenience, the invention will be described in connection with the production of yarns by the viscose process, though it is manifest that the invention is not restricted thereto.

The objects of this invention are accomplished, in general, by incoporating a resiniferous reagent, hereinafter more fully described, into a cellulosic solution and, after extruding the solution to produce a regenerated cellulose yarn of the desired shape and. containing the reagent, causing the reagent .by a thermal treatment to react with the cellulose whereby the cellulose is converted into a (relatively little) substituted derivative by forming bridg linkages between the cellulose chains. The resiniferous reagent contains bior poly-functional groups which will be converted into resiniform groups by polymerization, that is, high molecular weight groups obtained by linear bi-dimensional r tri-dimensional condensation.

The action of these bior poly-functional resiniferous reagents is similar to that of vulcanization agents in the rubber art, where isoprene chains greatly shortened during kneading are united to each other during vulcanization by bridge linkages formed by sulfur atoms.

The resiniferous reagents contemplated by this invention, moreover, should possess the following properties:

(1) Be completely soluble in the spinning solutions;

(2) Bestable in the presence of the constituents of the spinning solutions;

(3) Have a sufficiently low molecular weight so as not to affect the viscosity appreciably;

(4) Have a minimum effect on the index (or salt point) of the Spinning solutions in order not to decrease the stability of the latter;

(5) Precipitate out as completely as possible during coagulation of the spinning solution;

(6) Not undergo any modification in reactivity under the influence of the coagulating baths;

('7) Be practically insoluble in the finishing baths, and especially in the desulfurization bath;

(8) Be capable of reacting with the hydroxyl groups of the cellulose;

(9) Not degrade the cellulosic material.

The resiniferous reagents must be bior polyfunctional in order to undergo polymerization or resinification. Moreover, during thermal treatment of the coagulated products suitably fixed by acid baths, there must be produced simultaneously with polymerization a reaction with the free hydroxyl group of the cellulose similar to etherification.

In general, the resiniferous reagent is a bior polymethyloloxyaryl compound having the general formula:

onion).

wherein R is an aryl group, either cyclic or polycyclic, R is an alkyl, aryl or acyl group or hydrogen, and n is at least 2. The radical R may comprise two or more phenyl groups combined by direct saturation of their valences or by an oxygen, carbonyl, amine, hydrocarbon, etc. bridge or by polycyclic groups themselves united as explained above. Such reagents in the presence of heat, and preferably also in the presence of an acid catalyst, react with cellulose material containing free hydroxyl groups to form resiniform bridge linkages by simultaneous polymerization (internal condensation) and etherification of the hydroxyl groups in the cellulosic material. The cellulose derivative constituting the reaction product is herein termed resyl cellulose and probably has a constitution represented by the following general formula:

Cellulose radicalOR-O-cellulose radical wherein R designates a resiniform radical.

The reagents that have produced optimum results up to the present time are diand trimethylolphenols obtained by reacting phenols with two or three molecules of formaldehyde, in the form of Formol, per molecule of phenol preferably by the method of Manasse and Lederer (Berichte der deutschen chemischen Gesellschaft, 1894, vol. 27, p. 2409). These phenol alcohols preferably are slightly condensed, however not to the stage where they are in a resinous state. This condensation diminishes the solubility of the material in the coagulation bath in such a manner as to assure sufficient precipitation (of the order of 90%) during coagulation of the spinning solutions. However, condensation must be limited in such manner as to conserve the maximum number of active methylol groups, and the reagent must be completely soluble in dilute (from 5% to 10%) caustic soda aqueous solutions and ipso facto in viscose or other analogous alkaline solutions of cellulose derivatives.

When a different phenolic derivative is employed as the raw material, the poly-alcohol phenol is prepared in a similar manner to that previously described except that the quantity of Formol is determined by calculation of the maximum number of methylol radicals which can be fixed to the nucleus of the phenolic derivative used.

In carrying out the invention, the reagent is first prepared, then added in the desired quantity to the spinning solution, which is spun. After the yarn is fixed, it is subjected to the necessary liquid treatment, dried, and subjected to a thermal treatment, which may be included as part of the drying operation. It is during this latter treatment that the reaction between the reagent and the cellulose takes place.

The invention will now be described in greater detail particularly for the case of the utilization case.

Preparation of reagent of formaldehyde should be avoided, that is, the

quantity of formaldehyde should not exceed 3 molecules per molecule of phenol.

A solution of trimethylolphenol is prepared by known processes avoiding the formation of resin. This reaction may be carried out at temperatures of from C. to 80 C. in the presence of alkaline catalysts (NaOI-I,Ca0, etc.). Lower temperatures may be used by increasing the quantity of catalyst.

The phenol alcohol obtained is then subjected to polymerization carried out in acid medium in order to acquire the properties necessary for its incorporation in the spinning solutions. After neutralization of the alkali, it is heated for this purpose, but not to boiling, in the presence of weak acid catalysts having a pH of from 3 to 3.5 as a minimum.

Specifically, the neutralized liquid is rendered acid with concentrated lactic acid and is then heated at a temperature of from 96 C. to 98 C. for several hours. An emulsion forms after some time. cold water. First, liquid products are obtained in this manner but, as condensation progresses, they become more and more paste-like. The operation is completed when the emulsion tends to break, collecting at the bottom of the dispersed material. The free lactic acid is then neutralized with concentrated caustic soda carefully avoiding an excess of the latter and determining the pH after each addition.

Moreover, it was observed that the product must be absolutely free from free phenol and formaldehyde in order to avoid interferences in its utilization, namely, coloration of yarn, parasitic reactions, weakening of the yarn, etc. Also, salts must be eliminated. The product is Washed several times with boiling water for this purpose. After cooling, an ivory-colored cake of pearly appearance is found at the bottom of the vat.

The reaction is practically quantitative under the described condition. The product finally obcarefully filtered. This solution is also stable and may be stored for several days.

Incorporation of the semi-condensed products into the spinning solutions The required quantity of stock solution is added to the spinning solution in such manner as to have present a ratio of from 1:10 to 1:1 of reagent to cellulosic'mate'rial.

The incorporation of the'stock solution'into Samples are taken and are washed with 5 the spinning solution is effected in such manner as to produce an intimate mixture rapidly.

'If the mixture is made correctly, the salt point of the viscose is not affected (except slightly more rapid future evolution) and the variation in viscosity practically corresponds to that resulting from mixing two liquids having definite, de-

termined viscosities. The desired viscosity may be obtained by suitableregulation of the viscosity of the viscose.

Spinning The usual baths used in the viscose industry, such as the Muller type baths, are used for spinning viscose to which bior poly-functional resinferous reagents have been added.

The metric number of filaments of the yarn does notseem to influence the amount of precipitation of reagent. No appreciable difference has been observed between yarns of filament No. 6000 and 900.

Spinning is not more difiicult than in the case of the usual viscose and plugging of spinnerets is not increased if well-filtered stock solutions of reagent are used. It is advantageous to spin to a. number in the neighborhood of 5, that is, the usual index.

. Fixation In order to obtain complete insolubility of the reagent precipitated in the heart of the regenerated cellulose, it is of advantage to maintain the yarn in an acid state for a certain period of time before submitting it to finishing, for example, for from 4 to 24 hours. However, this is not essential and in certain cases the yarn may be treated immediately as explained below, for example, in the case of continuous spinning.

Finishing Desulfurization baths, such as the usual sodium sulfite baths, will be used but it is preferable to use baths which are only slightly alkaline in order to avoid losses by redispersion of the reagent.

Oiling is of great importance. In fact, some lubricating agents, such as sulfonated alcohols or polyamines, seem to favor definitely and to accentuate the action of the reagent on the cellulosic material. It may be supposed that these products, in reacting with the radicals forming resiniferous bridge linkages, for example, with the methylol groups not entering into reaction, accentuate the hydrophobic nature of the resiniform radicals. Similarly, softeners or plasticizers of the poly-alcohol type, such as glycerol, are capable of participating in the condensation reaction While conserving their activity. This fact is important in the manufacture of pellicles.

After oiling, the yarn is first dried as usual at from C. to C. After this drying, the hydrophobic nature of the yarn is not yet devel oped to a maximum, although considerable decrease in swelling is already observed.

It is pointed out that swelling is one of the properties determined by the conventional method and that the results obtained by this method have only a relative value. Primaryswelling is herein defined as the Weight of water retained by the. yarn in percentages of the dry cellulosic ma- .of water retained by the washed and dried yarn,

which has then been rewetted and redried under the same conditions as previously.

Primary swelling for regenerated cellulose is usually of the order of from'150 to'2'00, andsecondary swelling, of the order of from 100 to 120. For yarn obtained in accordance with the described process, secondar-y swelling is still of the same order or slightlylower after initial drying. However, it is greatly'lowered by the second drying, or thermal treatment,

Thermal treatment In principle, the yarn is later subjected'to'heating at from 100 C. to'l15"C. or even higher, for a neriod of time varying'with'the temperature and in the presence of traces of weak acids. Acids having a dissociation constant of as a'maximum change cellulose but slightly, audit is of advantage to use .themin order to prevent degradation of the yarn. At "a higher "temperature, the duration of the thermal treatment may be shorter, and'the quantity of acid catalyst'smaller.

In the case of yarn, heating may, for example, be carried out in a chamber at from 115 C. to 120 C. for from 2 to 3 hours at a pH of from 4 to 4.5 resulting from the addition of from 1 to 2 grs. of lactic acid or acetic acid to theoilingbath. If desired, the yarn may also be impregnated with a catalyst.

The thermal treatment'may also be carried out continuously at a higher temperature, such as of the order of from 130 C. to 140 C., at the same pH, by passage over heated rolls.

Moreover, it is not essential that the thermal treatment immediately follow the .usual finishing treatments. The yarn may be converted to manufactured products (fabrics, knit goods, etc.) and the thermal'treatm'ent thereafter 'applie'dto such manufactured products.

Whereas a temperature 'of from 115 C, to 120 C. seems necessary when using organic catalysts, a lower temperature may be used in the presence of stronger acids.

The resiniferous reagents to 'be added to the spinning solutions may be combined with other suitable products, particularly with other poly- 'merized and etherifiable substances capable of The examples herinafter described are illustrative embodiments of the invention, but it is obvious that these examples are in no way'limitative of the scope of this invention.

Example 1 (manufacture of continuous filaments) To a viscose solution containing "7% cellulose and 6% caustic soda were added 4% of a'stock solution of 60 grs. per liter of caustic soda and resiniferous material of the trimethylolp'henol type,.prepared as indicated above. Viscoseprepared in this manner contained 19% of dry reagent based on the cellulose. After ripening up to a salt point of '5, this viscose was spun through a spinneret having 1000 orifices, into a bath containing 130 grs of sulfuric acid, 250 grs. of sodium sulfate, and 10 grs. of zinc sulfate per liter .at a speed of 80 meters per minute,forming a product of metric number 5. The yarn was washed and then desulfurized with a sodium sulfite solution at 60 .C. Thereafter, it was oiled with a solution containing a product known by the trade name Soromine AF a fatty acid derivativesee Textil-Hilfsmitteltabellen, Berlin, 1938, p. 260) and 1 gr. of lactic acidper liter, and dried at C. The dried product was then subjected to a temperature of C. Thelproduct thus obtained had a swelling of 40.

Example 2 (manufacture of bristles) "To .a Viscose solution containing 7% cellulose and 6% caustic soda prepared from a slightly ripened or unripened alkali cellulose having a viscosity of the order of .centipoises, were added 6 parts of the aforementioned stock solution per 1 part of viscose. The viscose obtained in this manner contained about 32% of dry reagent with respect to the cellulose. It was spun in a coagulating bath containing 80 grs. of am- .monium sulfateand 40 grs. of sulfuric acid per liter, at a temperature of 40 C. and with a spin- Example 3 (manufactulre of thin pellicles) To a viscose solution, similar to that of Example 1, were added 4 parts, per 100 parts of viscose solution, of the stock solution of condensed trimethylolphenol, and then 6 parts of a 15% aqueous alcoholic solution of polyvinyl butyral Xanthogenate per 100 parts of viscose solution. The solution was ripened to a salt point of 2, then cast by means of a hopper into a bath containing 120 grs. of sulfuric acid and 200 grs. of sodium sulfate per liter. The resulting pellicle was suitably washed and desulfurized, as in Example 1, and was treated with glycerol in an aqueous bath containing 10% glycerol and also more than 2 grs. per liter of lactic acid. It was dried on a drumat a final temperature of C. The finished pellicle hada swelling of 45 and was quite insensitive to water.

Example 4 (manufacture of fiber with a high resz'nz'form radical content) A viscose solution, containing 7.5% of cellulose and 6.5% of caustic soda'and having a salt point of 5.5, was mixed with 18% of a stock solution of pre-condensed reagent, resulting in a content of about 90% of reagent with respect to the cellulose. The mixture was spun immediately at a rate of 70 meters per minute, using a spinneret'having 2500 orifices. The product, while in an acid state, was cut into pieces (staple), then washed and desulfurized, oiled as in Example 1, dried at 90 C., and finally treated at 115 C. for 2 hours. The fiber obtained in this manner had a swelling of 30. It was slightly yellowish, but was distinguished from ordinary fiber by its spring, that is, its resistance to crushing (and creasing).

In order to determine this crush resistance, a given weight of fiber was placed in a vessel, a weight (for example 5 kg.) was placed on it, and the weight then removed. The fiber of the present example returned to such a point that its final volume was 4 times greater than in the .case of ordinary fiber.

Kilometric Kslgli lggllfic Elasticity strg n th Ratio g WetzDry Dry Wet Per cent Per cent Unpolymenzed yarn. 16. 6 0.81 29 31 Treatment for 6 hours at 105 C 16.8 0. 84 29 32 Treatment for 2 hours at 120 C 16.7 0.81 31 Treatment for 1 hour at There are extremely numerous and varied applications of the invention. The decrease in secondary swelling of regenerated cellulose is of considerable interest in all the fields 0f application of regenerated cellulose products. As was mentioned above, the invention is applicable to the manufacture of yarn, threads, filaments, bristles, foils, casing, tubing, caps, bands, etc. The new cellulose derivatives, in accordance with the invention, are characterized primarily by their slight swelling. The latter, however, corresponds to a reduced sensitivity to water, steam, and to the variations in the relative humidity of the air. The wet strength of products of these new cellulose derivatives is high. Whereas in the case of artificial yarn of regenerated cellulose, the ratio between the wet and dry strength is usually of the order of from to it is or more for artificial yarns made in accordance with the invention. At the same time, the dry strength is increased more or less. The artificial yarn of the invention is also characterized by substantially no shrinkage on wetting, even with slightly alkaline aqueous liquids at boiling, such as washing liquors. Shrinkage on washing is one of the serious defects of artificial yarn and especially staple fiber articles, the dimensions of which may decrease under certain conditions from 10% rendering the articles non-usable.

Articles of natural textiles, such as cotton, wool, etc., are not immune to the mentioned defect, and one of the great advantages of the invention is to make possible the manufacture of knit goods and fabrics, etc., the dimensions of which are not in any way affected by washing, laundering, etc. even under rigid conditions. Moreover, unlike woolen fabrics, fabrics of artificial yarn, in accordance with the invention, do not felt when treated with aqueous liquids at boiling. Thus, squares of fabric made from fiber obtained according to the invention and'treatecl for 15 minutes by boiling in a, solution containing 5 grs. of Marseilles soap per liter, show a' negligible decrease in length and width, whereas squares of wool of identical texture were completely deformed and felted after an identical treatment.

Yarn made according tosthe invention, in the form of rayon and staple fiber, has an absolutely remarkable spring and resists crushing and to I creasing much better than ordinary artificial textiles. Elasticity on creasing and twisting is greatly increased. The articles, knitted fabrics, etcfmade from yarns of the invention have a much better appearance than those made of ordinary artificialyarns. On the other hand, their nervous feel enables them to compare favorably with natural textiles, especially wool.

Unlike artificial yarns obtained by application of 'stenosation, the affinity for dyes is generally not diminished and, on the contrary, dyeing in the case of certain direct dyes is facilitated and uniformity improved. Yarns madeaccording to the invention even possess a certain afiinity for dyes for cellulose acetate, clearly indicating that hereit is a matter of cellulose derivatives and not mixtures of cellulosic materials and resinous materials. It is to be noted that increase of the affinity for dyes is only manifested if the decrease in swelling is not carried to an excessive degree. In the latter case, a decrease in dye affinity may result.

The minimum sensitivity to humidity of yarns made according to the invention facilitates their conversion into knitted articles and fabrics. is well known, in fact, that in converting regenerated cellulose yarns, the relative humidity of the air of the rooms must be maintained rigorously constant in order to avoid irregularities in the fabric. In making yarn from staple fiber of regenerated cellulose, precaution must be taken to assure sufficient uniformity of the yarn. This factor is'much less important for staple fibers of the invention, since they are only slightly sensitive to humidity. Irregularities in tension during spinning are also less dangerous.

Moreover, textile articles made of yarns of the invention are wetted with much more difficulty than articles of ordinary artificial yarns and are not only comparable to articles of wool but also are even superior to them. On wetting, the drops slide without really wetting, and a long wetting time is necessary before the article is really wetted. Consequently, and also because of the smaller deformation on wetting, the serious defect of deformed regions, manifested, for example, by fabrics of rayon or fiber of ordinary viscose, is eliminated completely.

Bristles (which are usually monofilament) 50; made according to the invention are extremely interesting. Whereas bristles of regenerated cellulose, known up to the present, and even analogous bristles having a resin treatment were never suitable for brushes because of their very poor behavior on bending, rubbing, etc., the bristles made according to the invention behave very favorably and advantageously replace animal bristles, to which they are even superior because of their great regularity. The modulus of elasticity is double or more of that of regenerated "cellulose bristles, and the bending (folding) resistance is also much better. Bristles made according to the invention also compare favorably with artificial resin bristles and polymerized products in general, over which they also have the advantage of much lower cost.

The small sensitivity to water of'the bristles of: thin pellicles of regenerated cellulose were a great disadvantage in the useof thesepellicles-in certain industries where they could have found a considerable market. Attempts havebeenmade to overcome this by lacquering, coatinggorother surface treatments. However, excluding the difficulties involved in carrying this out and the additional complications in, the,- normal manufacturing process caused thereby, there is a serious question of cost, since such treatment increases the price considerably; Thexpresent'in- 'vention makes it possible, to obtain thin pellicles of regenerated cellulose which have very much reduced swelling properties, small sensitivity. to wetting, are extremely flexible; and slightly permeable to vapors of water andisolvents. These pel'- licles are suitable not only in'numerous applica tions, as wrappings for products sensitive to humidity, such as cigarets, sugar products, pastries, etc., but are also very interesting as wrap pings which must withstand the-low temperatures of refrigerating plants. The latter application requires products having good resistanceto wetting, being slightly permeable to water vapor and being able toiremain at low temperatures frequently. All these qualities are present in the pellicles made in accordance with this invention.

The pellicles of this invention may also be used advantageously in photography, motion pictures, sound recordings, etc., where regenerated cellulose pellicles have been used. They also can be used industrially, whereas the prior art regenerated cellulose pellicles, because of their great sensitivity to water and water vapor, could not be used. In fact, water and water vapor produce more or less great deformation of pellicles, and hence of the pictures orother recordings, and affect the quality of the reproduction. The pellicles of this invention, much less sensitive-towater, are thus in a position to find very interesting applications in .these industries, especially in combination with sensitization in the mass, producing images and recordings without visible opacity.

Pellicles made according to the invention are also of interest in other fields. Thus, they may be cut into-foils and fiber and used in making fashion articles whichwill be considerably less sensitive to water than knOWn articles. These pellicles may also be used' as membranes in dialysis because of their excellent resistance-to water and even toalkaline and acid liquids.

The process of the invention also lends itself to the manufacture of artificial casings which must have a sufficient wet strength to resist stuffing with sausage meat. Caps and bands for applications requiring rapid drying are also within the scope of the invention.

Certain additional applications in the field of molded. products may be considered, where deformation or drying was of disadvantage in the industrial application of cellulose.

The invention is applicable not only to regenerated" cellulose, but also more generally, as has been previously explained, to various products obtained by spinning, molding, etc., from solutions of cellulose derivatives containing free hydroxyl groups. In particular, it has very interesting applications in the case of certain cellulose derivatives which are easy to prepare and present certain advantages over cellulose xanthogenate from the point of view of facility and economy of conversion. These cellulose derivatives, namely hydroxyalkylor glycolcellulose, cellulocarboxylic acids, slightly substituted methyl and ethyl celluloses, have an excessive swelling, and products made' from their solutions in general have a low resistance, and especially a low wet strength. The incorporation of the aforementioned resiniferous compounds into their alkaline solutions, combined withthermal treatment of the finished products, results in products having greatly improved properties and capable of finding extremely interesting applications.

The invention may also be'applied in combinationwith other processes of spinning-solutionsof cellulose derivatives. In the case of dry spinning, the trimethylolphenols may be used directly without precondensation, the possibility of loss of reagent in precondensation not existing, while drying assures sufiicient precondensation to permit of finishing treatments without excessive losses.

In the case of pot spinning, with drawing by mobile fluids, of a superficially coagulated filament, it is essential to use precondensed products. More especially, in the case of viscous spun in this manner, slightly acidified baths are, used in combination with greatly ripened viscose, the slight acidity of the bath being sufficient to precipitate most of the reagent.

The process of the present invention, differs from known processes in which more or less soluble resols or resins which do not react. with the hydroxyl groups of cellulose and form an inert mass within the cellulosic material are dispersed in the spinning solutions. The object of such known processes was either to modify the affinity for dyes of the cellulosic material, or to fix mechanically impressed designs on the spun material, or to decreaseshrinkage on washing, or even to impart to the cellulosic material less absorbent properties. However, the decrease in swelling which may be achieved in this manner is much less significant than that obtained by the process of the present invention. It is to be noted in this connection that in using reagents in accordance with this invention the activity varies with the importance of the functional groups which enter into reaction.

As was stated above, the addition of various condensation products of phenol andformaldehyde to the spinning solutions has previously been suggested. In numerous-patents it was suggested especially to use the'condensation products of one molecule of phenol with approximately one molecule of formaldehyde, such products in principle being condensed in alkaline medium at boiling, and forming products of the resol type and containing no, or practically no, free methylol functions. The object andeifect ofadding these products to spinning solutions were improvement of dyeing properties ofthe yarn as well as fixation of printing, and, to a certain extent, the resistance to wetting of the fibers of regenerated cellulose by blocking its pores without modifying the chemicalproperties of the cellulose.

It was also suggested to eliminate the disadvantages of coloration of phenolic compounds under the influence of light by using condensation products obtained from 1 molecule of phenol and 3 molecules of formaldehyde or more in alkaline medium and also at boiling. Products of the type of high molecular weight resols were obtained, having only a fraction of their methylol groups in a free state and, consequently, no longer having any etherifying ability for the cellulosic hydroxyl groups. In addition, such processes included polymerization of these phenolic products during or after drying of the yarn by applying suitable temperatures, but either in the pres- GIICB Of alkali which served as catalyst for condensation, or in neutral medium, and in all cases never in acid medium which is the essential condition for obtaining etheriiication of the cellulosic hydroxyl groups of methylol groups. Finally, the number of methylol groups of these compounds was decreased considerably by resinification of the initial products.

The reagents in accordance with the invention are clearly defined by their chemical properties. In addition to the new chemical properties acquired by the yarn, the formation of a compound between regenerated cellulose and the reagent incorporated'into the spinning solution is proved by the fact that the tensile strength of the yarn only difiers very little from the corresponding property of yarn obtained in the absence of these reagents. In fact, as a general rule, any addition of foreign substances to spin-=- ning solutions (the charge, delustering agents, resins, protein substance, etc.) is manifested by a more or less great decrease in tensile strength and elasticity. This is not so for products. in accordance with this invention. According to this invention, artificial yarn may be produced using very large quantities of reagents (for example, from 40% to 50%) Without diminishing tensile strength, the yarn being even strengthened by 20% in the dry state and 40% or more in the Wet state. The resultant products are not heterogeneous mixtures and the added reagents combine chemically with the cellulosic material. The 'phenomena of plastic fiow manifested during drawing of the yarn are diminished and the modulus of elasticity increased.

In copending application Serial No. 649,777, filed on even date herewith, now Patent Number 2,495,233, there is disclosed, in general, resyl cel lulose and the preparation thereof from any cellulosic material. In copending application Serial No. 649,77 9, filed on even date herewith, now Patent No. 2,495,233, there is disclosed a process wherein already-prepared articles especially of regenerated cellulose, and such as yarns, filaments, bristles, films, etc., are converted to resyl cellulose. I

Since it is obvious that various changes and modifications may be made in the above description without departing from the nature or spirit from said spinning solution, and subjecting the structures to finishing treatment which includes thermal treatment to 'produce a resinification of the bridge linkages between the cellulose chains by the reaction of the hydroxyl groups of the cellulosic material with the polymethylolphenol.

2. A spinning solution consisting of an aqueous alkaline solution of cellulose xanthate and a nonresinous slightly condensed polymethylolphenol reagent capable of forming resiniform bridge linkages between cellulose chains and consisting essentially of a trimethylolphenol.

NICOLAS DRISCH. RENE FAYS.

REFERENCES CITED The following references are of record in the file oi? this patent:

UNITED STATES PATENTS Number Name Date 2,054,444 Pinten Sept. 15, 1936 2,190,672 Mehang Feb. 20, 1940 2,229,357 Wightman et al. Jan. 21, 1941 2,288,695 Fuller July 7, 1942 2,315,400 DAlelio Mar. 30, 1943 2,322,981 Ubbelohde June 29, 1943 2,360,376 Van Epps Oct. 1'7, 1944 OTHER REFERENCES Granger, Condensation of Phenols with Formaldehyde, Ind. and Chem., April 1932, pages 442 and 447. 

1. A METHOD OF PRODUCING FROM CELLULOSIC MATERIAL SHAPED STRUCTURES WHILE SHOW IMPROVED RESISTANCE TO SWELLING, WHICH COMPRISES DISSOLVING IN A VISCOSE SPINNING SOLUTION A NON-RESINOUS SLIGHTLY CONDENSED POLYMETHYLOPHENOL REAGENT CAPABLE OF FORMING RESINIFORM BRIDGE LINKAGES BETWEEN CELLULOSE CHAINS AND CONSISTING ESSENTIALLY OF A TRIMETHYLOLPHENOL, EXTRUDING SAID ESSENTIALLY OF A TRIMETHYLOLPHENAL, EXTRUDING SAID SPINNING SOLUTION IN THE SHAPE OF THE DESIRED STRUCTURE IN SOLUTION IN THE SHAPE OF THE DESIRED STRUCTURE IN SOLUTION IN THE SHAPE OF THE DESIRED STRUCTURE IN AN ACID BATH WHICH CO-PRECIPITATES BOTH THE COLLULOSIC SUBSTANCE AND THE POLYMETHYLOLPHENOL FROM SAID SPINNING SOLUTION, AND SUBJECTING THE STRUCTURES TO FINISHING TREATMENT WHICH INCLUDES THERMAL TREATMENT TO PRODUCE A RESINIFICATION OF THE BRIDGE LINKAGES BETWEEN THE CELLULOSE CHAINS BY THE REACTION OF THE HYDROXYL GROUPS OF THE CELLULOSIC MATERIAL WITH THE POLYMETHYLOLPHENOL. 